The present invention relates to the field of chemistry and, specifically, to the technology of organic synthesis; namely to the production of acetone obtained together with phenol during the decomposition of cumene hydroperoxide.
In addition to the basic products, which are acetone and phenol, an entire series of impurities having an adverse effect on the quality of the end product forms during the oxidation of cumene and subsequent decomposition of cumene hydroperoxide. After neutralization, acetone and phenol, the decomposition products of cumene hydroperoxide are fed to a fractionation column, in which they are separated into acetone raw material and phenol raw material fractions. Then, depending on the purification system used, the acetone raw material and phenol raw material fractions enter the appropriate stages of isolation and purification.
A method is known for purifying acetone raw material comprising subjecting the decomposition product to purification in two rectification columns wherein the acetone treated in the first rectification column is sent to the second rectification column, and purified acetone is discharged from the top of the second rectification column as a commercial product (see U.S. Pat. No. 3,215,745).
It is known, however, that use of simple distillation methods alone to purify acetone raw material is not completely effective since impurities, specifically, aliphatic aldehydes, olefins and a whole series of other impurities, remain in the treated acetone product, reducing its purity and quality.
Another known method of purifying acetone is a method in which acetone raw material is distilled in two columns. In this method, low molecular weight impurities are isolated in the first rectification column with the addition of an alkaline reagent to the first column. The remaining mixture of components (the still or bottom residues from the first rectification column) are subsequently sampled and charged or fed to the second rectification column in order to separate high molecular weight impurities and isolate purified, commercial acetone (see U.S. Pat. No. 6,340,777). In the method just described, it is possible to produce product acetone with a KT-test time of at least 5 hours when operating under optimum conditions. A disadvantage of this method is that the second rectification column operates at pressures below atmospheric pressure, which markedly increases operating costs and also significantly reduces the productivity of the second column compared to a column operated at atmospheric pressure (for example, it can reduce productivity up to 50% compared to a column with everything else being the same except operating pressure). Therefore, this method may produce acetone where the quality is not as high and/or the operating costs are higher and the productivity of the facility is lower due to the lower operating pressure. This is due to the use of the vacuum column to keep the aldol reversion reaction from occurring; there will be aldol reversion at atmospheric pressure.
There is a need to provide a simple and flexible method for further purifying acetone (to reduce the levels of impurities) without regard to the quality of the acetone raw material.